why bicubic sampling sucks

[ElFenix]

http://www.xs4all.nl/~bvdwolf/...sample/down_sample.htm

 

[andylawcc]

i am totally lost.

for the shots i've taken and want to downsize for uploading or emailing purposes, I just go to Image Size, and type in the new size (usually 1024x768 or 1280x960), oh and then quality = 9.

 

[fuzzybabybunny]

I use quadlogarithmic subatomic quasar sampling.

EDIT: I could have sworn I was replying to this topic in OT...

 

[SonicIce]

yea im always resizing a picture of concentric circles

 

[ElFenix]

Originally posted by: SonicIce
yea im always resizing a picture of concentric circles

the concentric circles just illustrate the issue rather well.

 

[rivan]

Originally posted by: ElFenix

Originally posted by: SonicIce
yea im always resizing a picture of concentric circles

the concentric circles just illustrate the issue rather well.

Concentric circles illustrate the weakness specific to that particular resampling method, while sampling down.

I would argue strongly against the article's assertion that:

The examples above use a very critical test target to simulate a real life scene, so the artifacts may be less visible with actual real life scenes, but the artifacts will be present nevertheless.

To take any transform's performance on one image and say it's representative of all images is short sighted, in my opinion.

The reason there are so many transform choices is that none of them are perfect for all images. Some perform better on subtle gradations, others do better on high contrast images. There is no one-size fits all, and I've had occasion to use most of PS's over time.

 

[ElFenix]

well it's not geometrically correct anyway

 

[Flipped Gazelle]

Originally posted by: ElFenix

Originally posted by: SonicIce
yea im always resizing a picture of concentric circles

the concentric circles just illustrate the issue rather well.

I did see this phenomenon occur once when downsampling a photo of a cardinal. One feather that had a lot of texture got mangled.